1. Field of the Invention
This invention relates to an optical device and, in particular to a laser-to-fiber coupler which guides an optical beam from a semi-conductor laser to an optical fiber used for transmitting the optical beam.
2. Description of the Prior Art
Rapid progress in the development of optical fiber and the semiconductor laser is accelerating a practical use of an optical communication systems.
However, there remain still many problem to be solved.
One of these problems a connection concerns between a semi-conductor laser and an optical fiber used as transmission line. A reflected optical beam generated in an optical fiber due to a fiber-to-fiber or to other device connections, a crack, bending of a fiber, and so on, may be introduced from the input surface of the optical fiber into the active region of the semiconductor laser such as a GaAs laser, and make the operation of the laser unstable. That is, when the reflected optical beam is introduced into the active region of the semiconductor, laser, the drive current to optical output characteristic, spectrum and modulated optical output wave of the laser are effected by the reflected optical beam. The effect is proportional to the quantity of the reflected beam.
This problem is a serious one for an optical communication system. Although many types of optical connectors have been proposed, there is no optical connector that has solved the above problem